shifting problem with Raleigh Super Gran Prix

I have a late 70s English made RSGP with original 5 speed freewheel, chain
and derailleurs. The bike only has about 1500 miles on it....most of which
have been put on in the past 3-4 months. Sudden interest in road cycling!!
;-)

I have no problem shifting smoothly from largest gear on rear to the
smallest---in other words shifting down. I do have a problem shifting from
smallest gear up to next smallest gear. Derailleur will chatter and skip to
the middle gear of the 5 gear freewheel. This has been going on for
several months...

Chain has been measured for wear and it checks good by both ruler and chain
measurement tool. Freewheel gears all look in good shape. Derailleurs
have been cleaned lubed and adjusted by local reasonably skilled mechanics
during recent overhaul...but the problem persists.

What is most likely causing this derailleur skip and are there any other
diagnostic tools to pinpoint the cause before I go buy replacements? Thanks
in advance.

email at

Adrian

Adrian Snyder wrote:

I have no problem shifting smoothly from largest gear on rear to the
smallest---in other words shifting down. I do have a problem shifting from
smallest gear up to next smallest gear. Derailleur will chatter and skip to
the middle gear of the 5 gear freewheel. This has been going on for
several months...

I think you're saying that when shifting from the largest cog, the chain
skips over the next-to-largerst cog.

Is there a big jump between the two biggest cogs (e.g., 34T to 28T)? What
kind of derailleur do you have?

When you shift from the other directiom, can you get the chain to engage
the problem cog without chattering?

Things to check:

Proper spacers between cogs? Bent teeth?

Is the derailleur hanger on the rear dropout bent?

Sight from behind and make sure the der cage is parallel to the cogs.

Check cable and housing for friction.

Art Harris